JPH11241669A - Starter for automobile engine incorporating improved overrun clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starter which is easy in structure, is small-sized, is light in weight and reduces cost by replacing a conventional roller type free- wheel with a driving bush and a pinion. SOLUTION: This starter is a starter for an automobile engine of a type in which a pinion 20 is freely rotatably connected with a driving bush 18 by a device 38 capable of relatively revolving the driving bush 18 and the pinion 20 when the revolving speed of the pinion 20 is faster than the driving bush 18. In this case, the device 38 has front and rear complementary friction surfaces 40, 42 supported by each of the pinion 20 and the driving bush 18. The pinion 20 is mounted so that the pinion 20 may freely move in a shaft direction relatively to the driving bush 18 connected with this pinion 20 and the two friction surfaces 40, 42 are elastically in press-contact with each other with prescribed force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a starter for an automobile engine. The invention is particularly capable of sliding axially on the drive shaft between its rear rest position and a forward position where the pinion of the overrun clutch engages a toothed ring on the flywheel of the internal combustion engine. An electric motor having a spiral spline for rotating a drive bush, which is a part of an overrun clutch, wherein if the rotation speed of the pinion is faster than the drive bush, the pinion is axially connected to the drive bush; The present invention relates to a starter in which a pinion is rotated together with a drive bush by a device capable of rotating the pinion relatively.

[0002]

2. Description of the Related Art In a conventional starter, a freewheel device is disposed between a pinion and a drive bush.
The primary function of the freewheel is to prevent the pinion from driving the starter motor at excessively high speeds that can cause damage when the engine is started.

A freewheel device provided with rollers attenuates sudden vibration of torque transmitted between a drive bush and a pinion.

[0004] This type of freewheeling device using rollers is particularly problematic when the excessive speed of the pinion with respect to the drive bush lasts for a long time, especially when the driver does not de-energize the starter immediately after starting the engine. Demonstrate high performance.

[0005] Recently, the cabin of automobiles is increasingly soundproofed from an acoustical point of view. However, due to this soundproofing effect, a driver hears fluctuations in the engine sound and starts the engine. These phenomena are even more common today than they are today, because they are prevented from recognizing.

Modern electronically controlled starters include means for detecting the start of the engine and controlling the contactor of the starter to return the overrun clutch to a rest position with a lever on which the contactor operates. .

[0007] Thus, a starter of the type described above comprises an electric control module for the motor, which automatically deenergizes the motor of the starter and at the same time returns the drive bush to a rear rest position in which the pinion does not engage the flywheel of the engine. I'm using

[0008]

Therefore, the duration of the "freewheel" state during operation is very short and does not depend on the reaction time of the driver.

[0009] The conventional freewheel arrangement, especially of the type using rollers, is therefore particularly advantageous in terms of short operating times.
It is over-designed for its purpose.

[0010] Therefore, freewheels of the type described above are too bulky and heavy for their function and are also costly.

The elimination of the freewheel device has already been proposed, but the elimination of the freewheel also eliminates the damping function, so that the resistance torque applied by the engine is present in the engine cylinder. Because of the periodic force of compressing the gas, it changes greatly during one revolution of the crankshaft, thereby impairing the mechanical durability of the starter and its operating noise level.

[0012] French Patent No. 2 066 173 also proposes an inertial overrun clutch arrangement in which the connecting ring has a conical rim with a reduced cross section in the direction towards the drive bush. At start-up, an enlarged conical drive bush acting on the resilient coupling ring engages the conical rim. In the above device, the compression spring abuts a stop ring fixed to the pinion and the armature shaft.

[0013] In the above arrangement, the compression spring has a dual role, that is, it exerts an initial stress on the two cones.
And return the overrun clutch to its rest position,
It has the role of holding it there. Thus, in the active position, the spring exerts the maximum force to prevent the transmission of overspeed to the armature, but provides the maximum force to increase the residual torque during freewheel operation. .

[0014] It is an object of the present invention to rotate the drive bush relative to the pinion when the rotation speed of the pinion is higher than the drive bush. Starter for an automotive engine of the type described, wherein the device between the drive bush and the pinion includes front and rear complementary friction surfaces supported by the pinion and the drive bush, respectively, wherein the pinion comprises:
This is mounted so as to be able to move in the axial direction relatively to the connected drive bush, and the two friction surfaces are elastically pressed against each other with a predetermined force, so that the rotational speed of the overrun clutch is driven. It is an object of the present invention to overcome the above-mentioned drawbacks by providing a starter that allows the drive bush to rotate relative to the pinion when faster than the bush.

[0015]

Other features of the present invention are as follows. The friction surface is a complementary surface of the two frustoconical shapes; The rear frusto-conical friction surface is convex and extends axially rearward from the front end of the drive bush, and the complementary front friction surface is concave and extends axially forward from the rear end of the drive bush. . The average diameter of the friction surface is approximately equal to the diameter of the basic cylinder of the pinion; -At least one of the two friction surfaces is coated with a friction lining. The coupling means between the pinion and the drive bush include axially oriented front and rear abutment surfaces supported by the drive bush and the pinion, respectively, between which the axially compressed and two frictions Spring means are provided for pressing the surfaces together. The front or rear abutment surface is an inner radial flange which is part of a coupling cap having another inner central flange facing the outer radial shoulder on the drive bush or pinion; is there. The drive bush is axially moved from rear to front by one end of a lever axially received in its radially oriented groove;

[0016] Other features and advantages of the present invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

In the following description, the same reference numerals are used for equivalent, similar or similar components.

[0018]

FIG. 1 shows a starter (12) for an automobile engine.
1 shows a driving shaft (10) driven by an electric motor (11).

The dynamic shaft (10) is rotatably mounted in a casing (14) by a needle bearing (16). The overrun clutch (19) slides axially on the front end of the moving shaft (10).

In the conventional configuration, the overrun clutch is
It includes a drive bush (18) and a pinion (20) provided in the axial direction of the rear end, that is, at the right end in FIG. The pinion (20) slides on a smooth cylindrical guide (22) at the front end of the drive shaft (10) on the shell bearing (24).

The drive bush (18) is a roller type freewheel device (26) which enables it to drive the pinion (20) in a rotational direction which is a drive direction of the driving shaft (10).
, And is axially connected to the pinion (20). The freewheel device (26) disengages the pinion (20) from the drive shaft (10) in the opposite direction.

The drive bush (18) itself is driven by two helical splines (28) (29) formed on the drive shaft (10) and in the inner cylindrical portion of the drive bush (18), respectively. It is rotationally driven by (10).

The drive bush (18) and the pinion (20) are driven by a command from a pivot fork (30) of a starter (12) which is started by a command from a contactor (32) having a conventional configuration, and a moving shaft (10). Glide over. These configurations and arrangements are known.

Due to the above configuration, the overrun clutch (19) constituting the connected pinion and the drive bush (18) has its rest position at the rear of FIG. 1 and the teeth of the pinion (20) being the engine. Between the front working position (corresponding to the axial displacement of the overrun clutch (19)) meshing with the toothed ring (not shown) of the flywheel;
1 can be slid axially toward the left side of FIG. 1 until the front transverse surface (34) of the pinion (20) abuts axially on a stop ring (36) supported on the drive shaft (10).

In the present invention, the roller type freewheel (2
It has been proposed to eliminate 6) and replace it with another device. FIG. 2 shows the first embodiment. According to the invention, the drive bush (18) and the pinion (20) are rotatably driven by a device (38) similar to a friction clutch (38) having complementary front and rear friction surfaces (40) and (42). Are linked.

The friction surface (40) is a frustoconical convex surface that is coaxial with the axis of the overrun clutch (19) and thus the axis of the pinion (20) supporting the friction surface (40). The toothed portion of the pinion (20) is integral with the main body of the pinion (20), and has an inner friction surface (4).
0) (see FIG. 2), which extends axially rearward toward the drive bush (18).

For this reason, the position of the pinion (20) in the axial direction toward the rear is limited by the rear annular lateral edge (46). The rear pipe part (44) has a cylindrical surface (48).
Radially outwardly and forward by a radial shoulder (50).

According to a known configuration, a drive bush (18)
Has a tubular body (52) with a spiral spline (29) formed therein and defined by a rear annular lateral surface (54) and a front annular lateral surface (56).

The tubular body (52) of the drive bush (18)
Are limited radially outwardly by a frusto-conical convex friction surface (42) extending axially rearward from the transverse front end (56) for about half of the axial length of the drive bush (18). The front part (left side in FIG. 2) is thicker than the rear part.

The frusto-conical friction surfaces (40) and (42) are coaxial and complementary. That is, they have the same cone angle. The axial lengths of the two frusto-conical friction surfaces, corresponding to the distance between the rear end (46) of the pinion (20) and the front end (56) of the drive bush, and their cone angles are determined by the frusto-conical friction surfaces ( The average diameter (D) of (40) and (42) is determined to be approximately equal to the diameter of the basic cylinder (CP) of the pinion (20).

The pinion (20) is axially connected to the drive bush (18) by, for example, a connection cap (58) formed by cutting and bending a thin plate. The cap (58) extends radially toward the annular cylindrical outer skirt (60) and the body of the pinion (20), and the front shoulder defines an inner periphery defining a rear tube portion (44) of the pinion (20). The part (50) has a radially inwardly facing front flange (62) facing axially.

The cap (58) further includes a frusto-conical rear shoulder (66) formed on the cylinder (68) of the drive bush (18) during assembly of the overrun clutch.
Above has a rear flange (64) clamped radially inward.

The cylinder (68) includes a drive bush (18)
Is formed in a bell shape, extends axially toward the front, and is joined to the front of the body (52) of the drive bush (18) by a radial rear wall (70). Its annular transverse edge at the front free end (72) has an inner surface portion facing the radial flange (62) of the clamping clamp cap (58) which determines the axial position of the cap relative to the drive bush (18) after clamping. Bearing surface.

According to the invention, the axially acting spring washer (74) is provided with a center-facing front shoulder (5) of the pinion (20).
0) and the opposing inner surface of the radial inner flange (62) of the clamp fastening cap (58) is axially contracted,
At a given axial force (F), the frusto-conical friction surfaces (40) and (4)
2) is elastically pressed against each other.

Axial rear part (52) of drive bush (18)
Has the same shape as the radial groove (76), which is relatively wide in the axial direction and receives the free end of the fork (30).

The groove (76) is directed forward by a radially oriented rear transverse surface (78) of the wall (50) and a ring (76) mounted on the thin tubular rear of the drive bush (18) body (52). 82), the position is limited in the backward axial direction by a radial outer flange (80) which is a part of the outer flange.

For this purpose, the ring (82) is connected to the tubular body (5).
2) a spring clip (88) having a front tubular cylinder (84) axially threaded to the rear, rear cylindrical portion (86) and fitted in a complementary groove in the cylindrical portion surface (86); ) Holds the drive bush (18) in the axial direction.

The cylinder (84) of the ring (82) is preferably a pressure fit at the rear of the tubular body (52) of the drive bush (18). If the drive bush (18) is made of plastic material, the cylinder (84) surrounds the rear of the tubular body (52) of the drive bush (18),
It counteracts the radially outward bursting force resulting from the reaction force between the helical teeth (28) of the drive shaft (10) and the helical teeth (29) of the drive bush (18).

In this case, the spring means provided with the compression spring washer (74) transmits the initial torque (C) from the drive bush (18) to the pinion (20) via the conical friction clutches (40), (42). I do. The value of the torque (C) is equal to the product of the design characteristic force (F) and the coefficient (K), in particular the mean diameter (D) and the coefficient of friction between the two surfaces (40) and (42). , And the cone angles of these surfaces.

At the start, the motor of the starter starts to rotate,
When the pinion (20), driven axially forward by the drive bush (18), begins to axially plunge into the starter ring on the engine flywheel, the initial torque is much lower than the torque required by the starter to drive the starter ring. With only torque (C), the overrun clutch can be screwed onto the drive shaft (10) along the spiral spline (28) to bring the pinion (20) into contact with the stop ring (36).

Then, the overrun clutch (19)
Cannot move further forward in the axial direction, that is, to the left in the figure, and the axial pressure of the clutch (38), that is, the axial force for pressing the frusto-conical friction surfaces (40) and (42) is reduced by the starter ring. , Increase with the resisting torque opposing the motor by the "nut and bolt" effect of the cooperation of the spiral splines (28) and (29), which convert the torque into axial force.

The torque that can be transmitted by the clutch device (38), which is greater than the torque to be transmitted, is, in particular, the cone angle, the coefficient of friction between the friction surfaces (40) and (42), and the torsion of the splines (28) and (29). Horns,
Obtained by choosing various geometric and manufacturing parameters. In such a situation, all the torque of the starter motor (11) is transmitted to the pinion (20) to start the engine.

When the engine is started, the overrun clutch (19) is held axially with the pinion (20) cooperating with the starter as long as the contactor (32) is energized. , The pinion (20) is the output shaft (10) of the starter motor (11)
(22) It rotates faster and overruns the clutch (1
9) can unscrew along the moving axis (10).

The axial force previously generated by the transmitted torque disappears, and the initial residual torque (C) (spring means (7
4) remains and is transmitted to the starter motor. The value of this initial residual torque (C) is low,
It is not sufficient to make the rotating part of the electric motor to communicate with 0) overspeed.

This overspeed condition, in which the friction clutch (38) operates effectively like a freewheel device, is based on the fact that the cone angle is reduced to the surface (40), taking into account the coefficient of friction between the friction surfaces (40) and (42). ) And (42) are large enough to prevent axial wedging, ie, the pinion (20), the drive bush (18), and the friction surfaces (40) and (42). Of course, when there is always the possibility of relatively slightly axial movement, it is possible.

Next, the embodiment shown in FIG. 3 will be described. In FIG. 3, the spring means comprises a rear abutment surface which is a radially inner flange (64) behind the cap (58);
A compression coil spring (74) is disposed axially between the drive bush (18) and a front abutment surface which is an opposite surface of the radial rim (90) outside the cylinder (68) of the body (52). ing.

In the embodiment shown in FIG. 4, the spring means again comprises a rear abutment surface which forms the rear center-facing inner flange of the cap (58) and an outer diameter of the front part of the drive bush (18) body (52). Spring washer (7) axially disposed between the rim (90) and the forward abutment surface forming the opposing annular surface of the rim (90).
4) is provided. The front surface (78) of the groove (76) is provided with a washer (74) that is axially held forward by the cylinder (84) of the ring (82).

Finally, the modification shown in FIG.
6), and provided on the front (78) and rear (80) sides of the groove, provided with two radially oriented flanges integral with the body (52) of the drive bush (18). Is different from the embodiment of FIG.

As a variant, not shown in the figures, the connecting cap (58) can be fixed to the drive bush by any means, for example by elastic interengagement, welding, gluing or the like. Also, instead of the spring washer (74) or the compression coil spring shown in FIG. 3, any equivalent spring means such as a ring, an elastomeric block or the like can be used.

Further, the frusto-conical friction surfaces (40) and (4)
2) can be exchanged. That is, the convex frustoconical surface follows the pinion, and the concave frustoconical surface drives the drive bush (1).
8).

Finally, in order to set the coefficient of friction between the friction surfaces (40) and (42) to a desired value or to improve the wear resistance of the friction clutch (18), the two surfaces (40) are used.
It goes without saying that one or both of (42) and (42) can be covered with a friction material lining.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a part of a conventional automobile starter in which an overrun clutch includes a roller-type freewheel device.

FIG. 2 is an axial sectional view of a first embodiment of the overrun clutch according to the present invention.

FIG. 3 is a sectional view similar to FIG. 2, showing a modified embodiment of the overrun clutch shown in FIG. 2;

FIG. 4 is a sectional view similar to FIG. 2, showing another modified embodiment of the over-by-run clutch shown in FIG. 2;

FIG. 5 is a cross-sectional view similar to FIG. 2, showing another modified embodiment of the overrun clutch shown in FIG. 2;

[Explanation of symbols]

 (10) Active shaft (11) Motor (12) Starter (14) Casing (16) Needle bearing (18) Drive bush (19) Overrun clutch (20) Pinion (22) Cylindrical guide (24) Shell bearing ( 26) Freewheel device (28) (29) Spiral spline (30) Pivot fork (32) Contactor (34) Pinion front (36) Retaining ring (38) Friction clutch (40) (42) Friction surface (44) Pipe (46) Annular lateral edge (48) Cylindrical surface (50) Front radial shoulder (52) Tubular body (54) Rear radial lateral (56) Front radial lateral (58) Connection cap (60) ) Annular cylindrical outer skirt (62) Front flange (64) Rear flange (68) Cylinder (70) Rear wall (72) Free end (74) Spring washer (76) Radial groove (78) Rear lateral surface (80) Radial outer flange (82) Ring (84) Front tubular cylinder (86) Rear cylindrical part (88) Spring clip (90) Outer radial rim (C) Initial torque (CP) Basic cylinder (D) Average diameter (F) Axial force (K) Coefficient of friction

Claims (6)

[Claims] An axle (22) is located on the axle (22) between a rear rest position and a forward position where the pinion (20) meshes with a toothed ring on a flywheel of the engine. An electric motor (11) having a helical spline (28) for rotationally driving a drive bush (18) which is part of an overrun clutch (19) slidable in the axial direction, wherein the pinion (20) comprises a drive bush (18). ) Is connected in the axial direction, and when its rotation speed is higher than that of the drive bush (18), the drive bush (18) and the pinion (20) can be relatively rotated by the device (38). A complementary front-rear friction surface (40), wherein the device (38) is two complementary frustoconical surfaces supported by a pinion (20) and a drive bush (18), respectively. (42), and the pinion (20) is axially movably mounted on a drive bush (18) connected thereto, and the two friction surfaces (40) (42) are A starter for an automobile engine elastically pressed against each other, wherein a connecting means (58) provided between the pinion (20) and the drive bush (18) respectively comprises a drive bush (18) ( 58) and pinion (20),
It includes front and rear contact surfaces (62) and (50) facing in the radial direction, and is axially compressed between them to press the two friction surfaces (40) and (42) together with a predetermined force (F). When the rotational speed of the overrun clutch is higher than that of the drive bush (18), the drive bush (18)
Starter, characterized in that it is equipped with spring means (74) allowing it to rotate with respect to the pinion (20). 2. The rear frusto-conical friction surface (42) is convex, extends axially rearward from the front end of the drive bush (18) (52), and has a front complementary friction surface (42). 2. The starter according to claim 1, wherein the starter has a concave shape and extends axially forward from a rear end of the drive pinion. 3. The starter according to claim 1, wherein the average diameter of the friction surfaces is substantially equal to the diameter of the basic cylinder of the pinion. 4. The starter according to claim 1, wherein at least one of the two friction surfaces is coated with a friction lining. 5. The front contact surface (62) or the rear contact surface is provided with a drive bush (18) (68) or a pinion (2).
0) an inner radial flange that is part of a coupling cap (58) having another inner radial flange (64) opposite the outer radial shoulder (66). The starter according to claim 1, wherein: 6. The drive bush (18) is pivoted from rear to front by one end of a lever axially received in a groove (76) facing in a radial direction of the drive bush (18) (82). The starter according to claim 1, wherein the starter can move in a direction.